BCD to Ascii and Ascii to BCD

c bcd

John · Jan 18, 2016 · Viewed 10.2k times · Source

I'm trying to convert a BCD to ascii and vice versa and saw a solution similar to this while browsing, but don't fully understand it. Could someone explain it?

void BCD_Ascii(unsigned char src, char *dest) {
         outputs = "0123456789"
        *dest++ = outputs[src>>4];
        *dest++ = outputs[src&0xf];
        *dest = '\0';
    }

Answer

The function converts a character in binary-coded decimal into a string.

First the upper 4 bits of src are obtained:

src>>4

The function then assumes the values those bits represent are in the range 0-9. Then that value is used to get an index in the string literal outputs:

outputs[src>>4];

The value is written into address which is pointed to by dest. This pointer is then incremented.

*dest++ = outputs[src>>4];

Then the lower 4 bits of src are used:

 src&0xf

Again assuming the values of those bits, are representing a value in range 0-9. And the rest is the same as before:

*dest++ = outputs[src&0xf];

Finally a 0 is written into dest, to terminate it.

BCD to Ascii and Ascii to BCD

Answer

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